The present invention relates to an input device to input the positional information. The present invention also relates to a liquid crystal display device which modulates the light by controlling the alignment of the liquid crystal and displays the visible information such as numerals, characters and patterns, and is provided with the above-mentioned input device. The present invention still further relates to the liquid crystal display device as mentioned above, in particular, of the type in which flexible transparent substrates such as plastic film are used as transparent substrates to hold the liquid crystal. The present invention is moreover concerned with an electronic device comprising such a liquid crystal display device.
(1) Background Art Related to Input Device and Liquid Crystal Display Device Using it
A CRT display is extensively used as a means to display the visible information in an electronic device such as a cash dispenser. A liquid crystal display device is extensively used as a means to display the visible information in electronic devices such as computer and electronic notebook. As a method to input various data in various electronic devices, an input method is known in which panel-shaped input devices are stacked on a visible information display device such as the CRT display and the liquid crystal display device, and the information is inputted by designating the position by pressing the desired position in the input panel of the input device by a pen or a finger when various visible information is displayed on the liquid crystal display device or the like. In performing the input method of this kind, the panel-shaped input devices are stacked directly on the liquid crystal display device, etc. in the conventional practice.
As the panel-shaped input device, a so-called film-glass type input device is conventionally known, in which a plastic film provided with an electrode terminal and a glass substrate provided with the electrode terminal are arranged opposite to each other with a clearance therebetween. In this input device, the positional information is inputted by usually pressing the plastic film side by a finger, etc. The so-called film-film type input device of the shape in which the substrate opposite to the plastic film on the input side comprises a plastic film is also known as the input device.
As a liquid crystal display device provided with the input device, a device in which an acrylic plate is arranged between a touch panel (i.e., an input device) and the liquid crystal display device is disclosed in the Japanese Unexamined Patent Publication No. 5-303464. In this conventional liquid crystal display device, the input device is prevented from being curved when the input device is pressed by a pen, etc., by providing the acrylic plate.
The above-mentioned film-glass type input device has a disadvantage that the glass is easy to break because a glass substrate is used on one side. On the contrary, the film-film type input device has an advantage that the input device is easy to handle because no film is broken. However, when the film-film type input device is directly stacked on the liquid crystal display device, etc., problems that the plastic film is degraded in a short time and damages such as cracking are easy to generate compared with the film-glass type input device if the input operation is repeated on the film-film type input device. A problem is further presented that the feeling during the input is not excellent because the stiff touch of the surface of the liquid crystal display device or the like is felt by an operator through the pen, etc. when the film-film type input device is directly installed on the liquid crystal display device, etc.
In the device disclosed in the Japanese Unexamined Publication No. 5-303464, i.e., the device provided with the acrylic plate between the liquid crystal display device and the touch panel, the above-mentioned problems are left unsolved that the plastic film of the input device is easy to degrade, and the input feeling is not excellent because the acrylic plate is made of hard material.
(2) Background Art Related to Liquid Crystal Display Device of the Structure Using Flexible Transparent Substrate Such as Plastic Film
In recent years, the liquid crystal display device is extensively used as a means to display the visible information in electronic devices such as computers and electronic notebooks. In the liquid crystal display device, a liquid crystal panel (i.e., the liquid crystal display device) is generally formed by sealing the liquid crystal in the clearance, the so-called cell gap, to be formed between a pair of transparent substrates, an IC for driving the liquid crystal is connected to the liquid crystal panel, and accessories such as a back light and a casing are further mounted on the liquid crystal panel.
A pair of above-mentioned transparent substrates are formed of the material difficult to deflect such as glass in some cases, or formed of the flexible material such as a plastic film in other cases. The transparent substrates formed of the plastic film have many advantages such as difficulty to crack, formation in thin structure, light weight, and formation in various shapes.
However, in the liquid crystal display device in which the flexible material such as plastic film is used, if the plastic film is poorly handled in building it in an electronic notebook or other electronic devices, abnormal external force is applied to the liquid crystal display device, problems are presented that a local recessed part is generated in the transparent substrate, and as a result, defective appearance by irregular color is generated, defective appearance such as dark dots caused by bubbles in the liquid crystal is generated, or cracks are generated in a transparent electrode. Cracks generated in the transparent electrode may lead to not only disconnection of wires, but also defective display, causing a problem.
Even after build-in of the liquid crystal display device in the electronic device is completed, the above-mentioned problems such as generation of irregular color, bubbles, etc. are presented if the local external force is applied to the transparent substrate of the liquid crystal display device by some reasons.
(3) Object of the Present Invention
The first object of the present invention is to solve problems related to the above-mentioned input device, and more specifically, in the film-film type input device and various devices using it, to prevent degradation of the plastic film in a short time, i.e., to improve the descriptive durability on the input device and to improve the inputting touch related to the input device.
The second object of the present invention is to solve the problems related to the liquid crystal display device of the structure using the above-mentioned flexible transparent substrate, and more specifically, to prevent generation of the irregular color on the display screen of the liquid crystal display device or generation of bubbles in the liquid crystal by mitigating the external force when the external force is applied to the liquid crystal display device using the flexible transparent substrate.
(1) To achieve the first object mentioned above, the input device related to the present invention is an input device in which a pair of plastic films stacked on each other with clearance are provided, one plastic film is pressed to display the positional information, and the other plastic film is stacked on the visible information display means. The input device is characterized in that a transparent elastic member is provided on the surface of the plastic film stacked on the visible information display means.
In the input device, the transparent elastic member is arranged on the outer side of the plastic film on the opposite side to the plastic film on the side to be pressed by a pen, etc., related to the film-film type input device, and concentration of the stress to be applied to the plastic films on both face and back sides when one plastic film is pressed by the pen, etc. in a small area can be avoided, and thus, degradation of the plastic film in a short time can be prevented. That means, the descriptive durability of the input device can be improved.
When one plastic film is pressed by the pen, etc., the transparent elastic member is elastically deformed according thereto, and soft and favorable touch can be obtained compared with the case where hard material such as glass is pressed by the pen, etc. That means, the input touch of the input device is improved.
In the input device of the above-mentioned constitution, the visible information display means includes the liquid crystal display device to display the visible information such as numerals, characters and patterns by controlling the alignment of the liquid crystal to modulate the light, and the CRT display to display the visible information using the CRT (Cathode Ray Tube).
(2) In the input device according to (1) above, the transparent elastic member such as silicone rubber and acrylic rubber can be used.
(3) In the input device according to (1) above, the thickness of the transparent elastic member is preferably not less than 0.5 mm to less than 2 mm. If the thickness is below 0.5 mm, neither of improvement of the descriptive durability nor improvement of the input touch can be obtained. If the thickness exceeds 2 mm, the clearance between the screen of the liquid crystal display device, etc., and the pressing point by the pen, etc., becomes excessive, and alignment of the desired point to be pressed in the screen with the actual pressing point may be unsuccessful. In particular, the problem will be presented remarkably when the pressing operation is performed watching the screen in the diagonal direction.
(4) In the input device according to (1) above, the Young""s modulus of the transparent elastic member is preferably not less than 1xc3x97104 N/m2 to less than 1xc3x97108 N/m2. The Young""s modulus of natural rubber is 9.0xc3x97106 N/m2, and the Young""s modulus of silicone rubber is 7.0xc3x97106 N/m2 respectively, and these elastic materials are especially preferable.
(5) Next, to achieve the first object mentioned above, the liquid crystal display device related to the present invention is provided with a liquid crystal display means and an input means. The liquid crystal display means is provided-with a pair of transparent substrates which are opposite to each other forming a cell gap therebetween, and a liquid crystal sealed in the cell gap. In addition, the input means is provided with a pair of plastic films stacked on each other with clearance. One plastic film is pressed to display the positional information while the other plastic film is stacked on the above-mentioned liquid crystal display means. The liquid crystal display device is characterized in that the transparent elastic member is provided between the above-mentioned liquid crystal display means and the above-mentioned input means.
(6) In the liquid crystal display device according to (5) above, the transparent elastic member such as silicone rubber and acrylic rubber can be used.
(7) In the liquid crystal display device according to (5) above, the thickness of the transparent elastic member is preferably not less than 0.5 mm to less than 2 mm.
(8) In the liquid crystal display device according to (5) above, the Young""s modulus of the transparent elastic member is preferably not less than 1xc3x97104 N/m2 to less than 1xc3x97108 N/m2. The Young""s modulus of natural rubber is 9.0xc3x97106 N/m2, and the Young""s modulus of silicone rubber is 7.0xc3x97106 N/m2 respectively, and these elastic materials are especially preferable.
(9) Next, to achieve the first object mentioned above, the electronic device related to the present invention includes the display device to display the visible information such as a computer, an electronic notebook, and a cash dispenser, e.g., the liquid crystal display device and the CRT display. The electronic device related to the present invention is characterized in that the liquid crystal display device including the constitution that the transparent elastic member is provided between the liquid crystal display means and the input means, is included as the constitution requirement.
(10) To achieve the second object mentioned above, the liquid crystal display device related to the present invention is characterized in that the transparent elastic member which is arranged on the outer side of one flexible transparent substrate and uniformly covers the flexible transparent substrate, and a transparent covering member which is arranged on the outer side of the transparent elastic member and uniformly covers the transparent covering member are provided in the liquid crystal display device having a pair of flexible transparent substrates opposite to each other so as to form the cell gap and the liquid crystal sealed in the cell gap.
In the liquid crystal display device, even when the external force is applied to the transparent covering member, the external force is absorbed by the transparent elastic member, and the external force is little transmitted to the flexible transparent substrate of the liquid crystal panel, and no local focus is applied to the flexible transparent substrate. As a result, generation of the irregular color of the displayed image and bubbles in the liquid crystal can be prevented.
In the above-mentioned constitution, the xe2x80x9cflexible transparent substratexe2x80x9d of the liquid crystal panel can be formed, e.g., of the plastic film of polycarbonate (PC), polyacrylate (PAr) and polyether sulfone (PES).
(11) In the liquid crystal display device according to (10) above, the transparent covering member is preferably lower in elasticity than the transparent elastic member, i.e., large in Young""s modulus.
(12) In the liquid crystal display device according to (10) above, the xe2x80x9ctransparent covering memberxe2x80x9d is a member provided on the outer side of the liquid crystal panel for the purpose of playing various roles, and comprises a protective plate to protect e.g., the flexible transparent substrate of the liquid crystal panel.
(13) The xe2x80x9ctransparent covering memberxe2x80x9d can be constituted by the input device to input the information such as numerals and characters. The input device includes e.g., a pair of transparent substrates stacked on each other with clearance, one of which is pressed to display the positional information, the other of which is arranged on the outer side of the liquid crystal panel so as to uniformly cover the flexible transparent substrate of the liquid crystal panel. The transparent substrate of the input device may be formed using the flexible material such as the plastic film, or may be formed using the non-flexible material such as glass.
(14) The xe2x80x9ctransparent covering memberxe2x80x9d can be constituted by a polarizer. In this case, the transparent elastic member is arranged in contact with the outer side of the flexible transparent substrate, and the polarizer is arranged on the outer side of the transparent elastic member.
(15) In the liquid crystal display device according to (10) above, the transparent elastic member can be formed of e.g., silicone rubber.
(16) In the liquid crystal display device according to (10) above, the thickness of the transparent elastic member is preferably not less than 0.5 mm to less than 2 mm. When the thickness is less than 0.5 mm, the effect to mitigate the external force becomes insufficient, while if the thickness is not less than 2 mm, handling becomes difficult, or the appearance can be damaged. In particular, when the transparent covering member to be arranged on the outer side of the transparent elastic member is the input device, and the thickness of the transparent elastic member is not less than 2 mm in thickness, the clearance between the screen of the liquid crystal panel and the pen input pressing point of the input device becomes excessive to make it difficult to perform the input work.
(17) In the liquid crystal display device according to (10) above, the Young""s modulus of the transparent elastic member is preferably not less than 1xc3x97104 N/m2 to less than 1xc3x97108 N/m2. The Young""s modulus of the above-mentioned silicone rubber is 7.0xc3x97106 N/m2, which is particularly preferable.
(18) Next, to achieve the second object mentioned above, the electronic device related to the present invention is characterized in that the electronic device is an arbitrary device to use the liquid crystal display device as the display device to display the visible information such as a computer and an electronic notebook, the liquid crystal display device includes a pair of flexible transparent substrates to seal the liquid crystal, the transparent elastic member is arranged on one outer side of the flexible transparent substrates, and the transparent covering member such as the protective plate and the input device is arranged on the outer side of the transparent elastic member.